Histological and immunohistochemical analyses for hypertrophy of mesenchymal stem cell aggregate culture after chondrogenic induction. After genetic modification with (a) Ad.GFP (negative control), (b) Ad.IHH (IHH), (c) Ad.IHH + Ad.TGF-β1 (IHH + TGF-β1), (d) Ad.IHH + Ad.BMP-2 (IHH + BMP-2), or (e) Ad.TGF-β1 or Ad.BMP-2 only (positive control; TGF-β1 or BMP-2) at 5 × 102 virus particles/cells, the aggregate cultures were processed and stained at culture days 10 and 21 for collagen type × (left panels) and alkaline phosphatase (right panels). Regions of positive staining appear brown (left panels) or blue (right panels). Panels are reproduced at low (50×; bar = 200 μm) and high (200×; bar = 50 μm) magnification as indicated. Ad., adenoviral vector; BMP, bone morphogenetic protein; IHH, Indian hedgehog; TGF-β, transforming growth factor beta.
Steinert et al. Arthritis Research & Therapy 2012 14:R168 doi:10.1186/ar3921